Extract method to get the table name for a class
Extract method to get a sequence name from a class' ID properties

For when there's no metaDB info for a class' table, it walks up the
ancestry of the class, and uses the ID properties to get the column
names, and assummes they must be the table primary keys.

From there, it guesses the sequence name
extract a method to get the sequence name for a class name
RDBMS data sources now send a signal when they're getting the value for a sequence
RDBMS data sources now send a signal when retrieving the next value from a sequence fails
Speed up the test by allowing fractional sleep times